java.lang.Object | |
↳ | android.nfc.NdefRecord |
Represents an immutable NDEF Record.
NDEF (NFC Data Exchange Format) is a light-weight binary format, used to encapsulate typed data. It is specified by the NFC Forum, for transmission and storage with NFC, however it is transport agnostic.
NDEF defines messages and records. An NDEF Record contains typed data, such as MIME-type media, a URI, or a custom application payload. An NDEF Message is a container for one or more NDEF Records.
This class represents logical (complete) NDEF Records, and can not be
used to represent chunked (partial) NDEF Records. However
NdefMessage(byte[])
can be used to parse a message
containing chunked records, and will return a message with unchunked
(complete) records.
A logical NDEF Record always contains a 3-bit TNF (Type Name Field) that provides high level typing for the rest of the record. The remaining fields are variable length and not always present:
Helpers such as createUri(Uri)
, createMime(String, byte[])
and createExternal(String, String, byte[])
are included to create well-formatted
NDEF Records with correctly set tnf, type, id and payload fields, please
use these helpers whenever possible.
Use the constructor NdefRecord(short, byte[], byte[], byte[])
if you know what you are doing and what to set the fields individually.
Only basic validation is performed with this constructor, so it is possible
to create records that do not confirm to the strict NFC Forum
specifications.
The binary representation of an NDEF Record includes additional flags to
indicate location with an NDEF message, provide support for chunking of
NDEF records, and to pack optional fields. This class does not expose
those details. To write an NDEF Record as binary you must first put it
into an NdefMessage
, then call toByteArray()
.
NdefMessage
and NdefRecord
implementations are
always available, even on Android devices that do not have NFC hardware.
NdefRecord
s are intended to be immutable (and thread-safe),
however they may contain mutable fields. So take care not to modify
mutable fields passed into constructors, or modify mutable fields
obtained by getter methods, unless such modification is explicitly
marked as safe.
Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
short | TNF_ABSOLUTE_URI | Indicates the type field contains an absolute-URI BNF construct defined by RFC 3986. | |||||||||
short | TNF_EMPTY | Indicates the record is empty. | |||||||||
short | TNF_EXTERNAL_TYPE | Indicates the type field contains an external type name. | |||||||||
short | TNF_MIME_MEDIA | Indicates the type field contains a media-type BNF construct, defined by RFC 2046. | |||||||||
short | TNF_UNCHANGED | Indicates the payload is an intermediate or final chunk of a chunked NDEF Record. | |||||||||
short | TNF_UNKNOWN | Indicates the payload type is unknown. | |||||||||
short | TNF_WELL_KNOWN | Indicates the type field contains a well-known RTD type name. |
[Expand]
Inherited Constants | |||||||||||
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From interface
android.os.Parcelable
|
Fields | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
CREATOR | |||||||||||
RTD_ALTERNATIVE_CARRIER | RTD Alternative Carrier type. | ||||||||||
RTD_HANDOVER_CARRIER | RTD Handover Carrier type. | ||||||||||
RTD_HANDOVER_REQUEST | RTD Handover Request type. | ||||||||||
RTD_HANDOVER_SELECT | RTD Handover Select type. | ||||||||||
RTD_SMART_POSTER | RTD Smart Poster type. | ||||||||||
RTD_TEXT | RTD Text type. | ||||||||||
RTD_URI | RTD URI type. |
Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Construct an NDEF Record from its component fields.
| |||||||||||
This constructor was deprecated
in API level 16.
use
NdefMessage(byte[]) instead.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Create a new Android Application Record (AAR).
| |||||||||||
Create a new NDEF Record containing external (application-specific) data.
| |||||||||||
Create a new NDEF Record containing MIME data.
| |||||||||||
Create a new NDEF record containing UTF-8 text data.
| |||||||||||
Create a new NDEF Record containing a URI.
| |||||||||||
Create a new NDEF Record containing a URI.
| |||||||||||
Describe the kinds of special objects contained in this Parcelable's
marshalled representation.
| |||||||||||
Returns true if the specified NDEF Record contains
identical tnf, type, id and payload fields.
| |||||||||||
Returns the variable length ID.
| |||||||||||
Returns the variable length payload.
| |||||||||||
Returns the 3-bit TNF.
| |||||||||||
Returns the variable length Type field.
| |||||||||||
Returns an integer hash code for this object.
| |||||||||||
This method was deprecated
in API level 16.
use
toByteArray() instead
| |||||||||||
Map this record to a MIME type, or return null if it cannot be mapped.
| |||||||||||
Returns a string containing a concise, human-readable description of this
object.
| |||||||||||
Map this record to a URI, or return null if it cannot be mapped.
| |||||||||||
Flatten this object in to a Parcel.
|
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.lang.Object
| |||||||||||
From interface
android.os.Parcelable
|
Indicates the type field contains an absolute-URI BNF construct defined by RFC 3986.
When creating new records prefer createUri(Uri)
,
since it offers more compact URI encoding
(#RTD_URI allows compression of common URI prefixes).
Indicates the record is empty.
Type, id and payload fields are empty in a TNF_EMPTY record.
Indicates the type field contains an external type name.
Used to encode custom payloads. When creating new records
use the helper createExternal(String, String, byte[])
.
The external-type RTD format is specified in NFCForum-TS-RTD_1.0.
Note this TNF should not be used with RTD_TEXT or RTD_URI constants. Those are well known RTD constants, not external RTD constants.
Indicates the type field contains a media-type BNF construct, defined by RFC 2046.
Use this with MIME type names such as "image/jpeg", or
using the helper createMime(String, byte[])
.
Indicates the payload is an intermediate or final chunk of a chunked NDEF Record.
TNF_UNCHANGED can not be used with this class
since all NdefRecord
s are already unchunked, however they
may appear in the binary format.
Indicates the payload type is unknown.
NFC Forum explains this should be treated similarly to the "application/octet-stream" MIME type. The payload type is not explicitly encoded within the record.
The type field is empty in an TNF_UNKNOWN record.
RTD Alternative Carrier type. For use with TNF_WELL_KNOWN.
RTD Handover Carrier type. For use with TNF_WELL_KNOWN.
RTD Handover Request type. For use with TNF_WELL_KNOWN.
RTD Handover Select type. For use with TNF_WELL_KNOWN.
RTD Smart Poster type. For use with TNF_WELL_KNOWN.
RTD Text type. For use with TNF_WELL_KNOWN.
RTD URI type. For use with TNF_WELL_KNOWN.
Construct an NDEF Record from its component fields.
Recommend to use helpers such as {#createUri} or
{createExternal(String, String, byte[])
where possible, since they perform
stricter validation that the record is correctly formatted
as per NDEF specifications. However if you know what you are
doing then this constructor offers the most flexibility.
An NdefRecord
represents a logical (complete)
record, and cannot represent NDEF Record chunks.
Basic validation of the tnf, type, id and payload is performed as per the following rules:
TNF_EMPTY
cannot have a type,
id or payload.TNF_UNKNOWN
or 0x07
cannot have a type.TNF_UNCHANGED
are not allowed
since this class only represents complete (unchunked) records.
If any of the above validation
steps fail then IllegalArgumentException
is thrown.
Deep inspection of the type, id and payload fields is not performed, so it is possible to create NDEF Records that conform to section 3.2.6 but fail other more strict NDEF specification requirements. For example, the payload may be invalid given the tnf and type.
To omit a type, id or payload field, set the parameter to an empty byte array or null.
tnf | a 3-bit TNF constant |
---|---|
type | byte array, containing zero to 255 bytes, or null |
id | byte array, containing zero to 255 bytes, or null |
payload | byte array, containing zero to (2 ** 32 - 1) bytes, or null |
if a valid record cannot be created |
This constructor was deprecated
in API level 16.
use NdefMessage(byte[])
instead.
Construct an NDEF Record from raw bytes.
This method is deprecated, use NdefMessage(byte[])
instead. This is because it does not make sense to parse a record:
the NDEF binary format is only defined for a message, and the
record flags MB and ME do not make sense outside of the context of
an entire message.
This implementation will attempt to parse a single record by ignoring
the MB and ME flags, and otherwise following the rules of
NdefMessage(byte[])
.
data | raw bytes to parse |
---|
FormatException | if the data cannot be parsed into a valid record |
---|
Create a new Android Application Record (AAR).
This record indicates to other Android devices the package that should be used to handle the entire NDEF message. You can embed this record anywhere into your message to ensure that the intended package receives the message.
When an Android device dispatches an NdefMessage
containing one or more Android application records,
the applications contained in those records will be the
preferred target for the ACTION_NDEF_DISCOVERED
intent, in the order in which they appear in the message.
This dispatch behavior was first added to Android in
Ice Cream Sandwich.
If none of the applications have a are installed on the device, a Market link will be opened to the first application.
Note that Android application records do not overrule
applications that have called
enableForegroundDispatch(Activity, PendingIntent, IntentFilter[], String[][])
.
packageName | Android package name |
---|
Create a new NDEF Record containing external (application-specific) data.
Use this method to encode application specific data into an NDEF Record. The data is typed by a domain name (usually your Android package name) and a domain-specific type. This data is packaged into a "NFC Forum External Type" NDEF Record.
NFC Forum requires that the domain and type used in an external record are treated as case insensitive, however Android intent filtering is always case sensitive. So this method will force the domain and type to lower-case before creating the NDEF Record.
The unchecked exception IllegalArgumentException
will be thrown
if the domain and type have serious problems, for example if either field
is empty, so always catch this
exception if you are passing user-generated data into this method.
There are no such restrictions on the payload data.
For efficiency, This method might not make an internal copy of the data byte array, so take care not to modify the data byte array while still using the returned NdefRecord. Reference specification: NFCForum-TS-RTD_1.0
domain | domain-name of issuing organization |
---|---|
type | domain-specific type of data |
data | payload as bytes |
if either domain or type are empty or invalid |
Create a new NDEF Record containing MIME data.
Use this method to encode MIME-typed data into an NDEF Record, such as "text/plain", or "image/jpeg".
The mimeType parameter will be normalized with
normalizeMimeType(String)
to follow Android best
practices for intent filtering, for example to force lower-case.
However the unchecked exception
IllegalArgumentException
may be thrown
if the mimeType parameter has serious problems,
for example if it is empty, so always catch this
exception if you are passing user-generated data into this method.
For efficiency, This method might not make an internal copy of the mimeData byte array, so take care not to modify the mimeData byte array while still using the returned NdefRecord.
mimeType | a valid MIME type |
---|---|
mimeData | MIME data as bytes |
if the mimeType is empty or invalid |
Create a new NDEF record containing UTF-8 text data.
The caller can either specify the language code for the provided text, or otherwise the language code corresponding to the current default locale will be used. Reference specification: NFCForum-TS-RTD_Text_1.0
languageCode | The languageCode for the record. If locale is empty or null, the language code of the current default locale will be used. |
---|---|
text | The text to be encoded in the record. Will be represented in UTF-8 format. |
IllegalArgumentException | if text is null |
---|
Create a new NDEF Record containing a URI.
Use this method to encode a URI (or URL) into an NDEF Record.
Uses the well known URI type representation: TNF_WELL_KNOWN
and RTD_URI
. This is the most efficient encoding
of a URI into NDEF.
The uriString parameter will be normalized with
normalizeScheme()
to set the scheme to lower case to
follow Android best practices for intent filtering.
However the unchecked exception
IllegalArgumentException
may be thrown if the uriString
parameter has serious problems, for example if it is empty, so always
catch this exception if you are passing user-generated data into this
method.
Reference specification: NFCForum-TS-RTD_URI_1.0
uriString | string URI to encode. |
---|
if the uriString is empty or invalid |
Create a new NDEF Record containing a URI.
Use this method to encode a URI (or URL) into an NDEF Record.
Uses the well known URI type representation: TNF_WELL_KNOWN
and RTD_URI
. This is the most efficient encoding
of a URI into NDEF.
The uri parameter will be normalized with
normalizeScheme()
to set the scheme to lower case to
follow Android best practices for intent filtering.
However the unchecked exception
IllegalArgumentException
may be thrown if the uri
parameter has serious problems, for example if it is empty, so always
catch this exception if you are passing user-generated data into this
method.
Reference specification: NFCForum-TS-RTD_URI_1.0
uri | URI to encode. |
---|
if the uri is empty or invalid |
Describe the kinds of special objects contained in this Parcelable's marshalled representation.
Returns true if the specified NDEF Record contains identical tnf, type, id and payload fields.
obj | the object to compare this instance with. |
---|
true
if the specified object is equal to this Object
; false
otherwise.Returns the variable length ID.
Returns an empty byte array if this record does not have an id field.
Returns the variable length payload.
Returns an empty byte array if this record does not have a payload field.
Returns the variable length Type field.
This should be used in conjunction with the TNF field to determine the payload format.
Returns an empty byte array if this record does not have a type field.
Returns an integer hash code for this object. By contract, any two
objects for which equals(Object)
returns true
must return
the same hash code value. This means that subclasses of Object
usually override both methods or neither method.
Note that hash values must not change over time unless information used in equals comparisons also changes.
See Writing a correct
hashCode
method
if you intend implementing your own hashCode
method.
This method was deprecated
in API level 16.
use toByteArray()
instead
Return this NDEF Record as a byte array.
This method is deprecated, use toByteArray()
instead. This is because the NDEF binary format is not defined for
a record outside of the context of a message: the MB and ME flags
cannot be set without knowing the location inside a message.
This implementation will attempt to serialize a single record by always setting the MB and ME flags (in other words, assume this is a single-record NDEF Message).
Map this record to a MIME type, or return null if it cannot be mapped.
Currently this method considers all TNF_MIME_MEDIA
records to
be MIME records, as well as some TNF_WELL_KNOWN
records such as
RTD_TEXT
. If this is a MIME record then the MIME type as string
is returned, otherwise null is returned.
This method does not perform validation that the MIME type is actually valid. It always attempts to return a string containing the type if this is a MIME record.
The returned MIME type will by normalized to lower-case using
normalizeMimeType(String)
.
The MIME payload can be obtained using getPayload()
.
Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression:
getClass().getName() + '@' + Integer.toHexString(hashCode())
See Writing a useful
toString
method
if you intend implementing your own toString
method.
Map this record to a URI, or return null if it cannot be mapped.
Currently this method considers the following to be URI records:
TNF_ABSOLUTE_URI
records.TNF_WELL_KNOWN
with a type of RTD_URI
.TNF_WELL_KNOWN
with a type of RTD_SMART_POSTER
and containing a URI record in the NDEF message nested in the payload.
TNF_EXTERNAL_TYPE
records.This method does not perform validation that the URI is actually valid: it always attempts to create and return a URI if this record appears to be a URI record by the above rules.
The returned URI will be normalized to have a lower case scheme
using normalizeScheme()
.
Flatten this object in to a Parcel.
dest | The Parcel in which the object should be written. |
---|---|
flags | Additional flags about how the object should be written.
May be 0 or PARCELABLE_WRITE_RETURN_VALUE .
|